Carpet calculator
Work out how much carpet to order for one room or several: the square yards off the roll, the length of each cut, and how many seams each room needs.
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How the carpet amount is worked out
Carpet comes off a roll of fixed width, 12 feet in most of North America (15 feet for some styles, 4 or 5 metres elsewhere), so you buy whole strips, not just the floor area. That is why carpet usually needs more than the 7% or so added for other flooring laid straight.
Each room is laid in strips the width of the roll. A 6" trimming allowance is added to the room's length and width, the number of strips across the room is rounded up, and each strip is cut to the room's length. The calculator tries both directions and keeps the one that uses less carpet (or has fewer seams when they tie).
The total is the roll length times its width, shown in square yards (9 sq ft each), the way carpet is priced in the US. Leftover strip width isn't reused in other rooms, so the result is a safe upper limit: an installer's seaming diagram can sometimes fit closets and small rooms into offcuts.
Seams are where strips meet. The calculator counts them per room so you can see when a different roll width or direction would avoid one in a main room.
Tips
- Carpet pile should run the same way in every room it flows between, and towards the main light source to hide seams.
- Stairs are measured separately: each step takes its tread and riser wrapped as one piece, so ask the installer to add them to the order.
- Order the pad by floor area, not by carpet area: it is laid without the strip offcuts.
- Doorways between rooms that share carpet need a seam or a transition: show the installer where you want them.
Do this from a scan instead
Scan the rooms or draw them, and vPlan AR gives every room's exact outline and area, so the installer works from real dimensions instead of a sketch. The material takeoff lists the floor finish per room, and the plan PDF shows each room's size for the seaming diagram.
Frequently asked questions
How much carpet do I need for a 12×10 room?
On a 12' roll, one strip 12' 6" long covers it (the room plus trim), so 150 sq ft or about 17 square yards, though the floor is only 120 sq ft.
Why do I need more carpet than my floor area?
Because carpet is cut from a roll of fixed width. A room 13' wide on a 12' roll needs two full strips, and the rest of the second strip is an offcut. Trimming at the walls adds a little more.
How much carpet for a 15×13 living room?
On a 12' roll it takes two strips 13' 6" long with one seam: 324 sq ft, or 36 square yards. On a 15' roll it fits in one strip with no seam.
How many square feet are in a square yard?
Nine: a square yard is 3 feet by 3 feet. Divide square feet by 9 to get square yards.
Guides
- How to Work Out Flooring, Paint and Baseboard Quantities from a Floor PlanFlooring needs waste for its pattern, paint needs the doors and windows taken off each wall, and baseboard stops at every doorway. Here is how to work out all three from a floor plan, by hand and in vPlan AR.
- How to Calculate the Square Footage of a HouseMultiply each room's length by its width and add the rooms up. Here is how to handle irregular rooms, what to include and leave out, why interior and exterior figures differ, and a worked example.